Systems, methods and computer program products for heart monitoring

ABSTRACT

The present invention provides systems, methods and computer program products for monitoring a heart. According to one embodiment, the system includes an implantable registering unit. The registering unit comprises a first controller structured to register an electrical signal from the heart. The system includes a second controller in operable communication with the first controller. The second controller comprises a data repository structured to receive data corresponding to the registered electrical signal and being structured to store the data. The data repository stores data corresponding to a baseline electrical signal of the heart. The second controller is structured to receive the data from the first controller corresponding to the registered electrical signal and to compare the registered electrical signal to the baseline electrical signal to determine whether the heart is functioning properly.

This application claims the benefit of provisional application No.60/550,533 filed Mar. 5, 2004.

FIELD OF THE INVENTION

The present invention relates generally to medical apparatus and methodsfor monitoring and evaluating cardiac function and, more particularly,to non-invasive apparatus and methods for monitoring and evaluating thecardiac function of heart transplant and congestive heart failurepatients, detecting heart failure in such patients and providing anappropriate warning to the patient and/or physician in the event ofactual or anticipated heart failure, and/or administering therapeuticdrugs to the patient to treat the patient's condition.

BACKGROUND OF THE INVENTION

Cardiovascular disease if the leading cause of death for both men andwomen in the U.S. today and claims more lives each year than the nextfive leading causes of death combined.

In the United States, nearly 5 million patients have been diagnosed withheart failure. Each year more than 500,000 new cases are recognized.This represents, by far the fastest growing area of cardiology. As manyas 20% of these patients qualify for an implanted device, either animplantable pacemaker or implantable cardiac defibrillator (“ICD”) or abiventricular pacemaker/ICD, and a fortunate percent of those severelysymptomatic individuals will go on to cardiac transplant.

The primary diagnoses associated with heart transplantation are coronaryartery disease (45%) and cardiomyopathy (45%), with congenital heartdisease accounting for 8% and approximately 3% for retransplantation.

Each year approximately 2,500 cardiac transplants are performed in theUnited States and this number approaches 5,000 worldwide. One-yearsurvival is approximately 85% in experienced transplant centers, with afive-year survival rate approaching approximately 70%. The most commoncause of death is infection, followed by acute rejection. Althoughtechnology exists to treat bradycardia and tachycardia, i.e., pacemakersand defibrillators, respectively, the currently available apparatus andmethods for monitoring a transplanted heart or for assisting incongestive heart failure assessment are quite limited and, for the mostpart, require the patient to undergo extensive invasive procedures orrepetitive visits to a hospital or other medical facility which can beexpensive.

Known methods for monitoring patients who receive a heart transplantgenerally involve an invasive procedure called endomyocardial biopsy(“EMB”). EMB procedures typically require an invasive biopsy of thetransplanted heart in which the patient is taken to a catheterizationlaboratory and a large blood vessel (usually in the neck) is cannulatedallowing a biopsy catheter to be advanced into the right side of theheart. Several small pieces or bites of the myocardium are sampledduring the EMB, which are then sent for pathological evaluation. Similarinvasive procedures are required of patients suffering from congestiveheart failure, including catheterization to evaluate pressures insidethe heart.

As discussed above, the rejection of a transplanted heart by thepatient's body is one of the leading causes of death during the firstyear following the transplant. In order to detect early rejection of atransplanted heart, multiple EMBs are performed at regular,predetermined intervals. The typical patient undergoes up to twenty (20)EMBs during the first year. After the first year, even patients who havenot experienced a rejection episode continue to require periodic EMBs toinsure normal function of the transplanted heart. Although EMBs detectrejection and allow treatment in order to prevent death of thetransplant patient, EMBs themselves result in a substantial risk ofbleeding, infection, cardiac perforation, and other morbiditiesincluding death. In addition, this catheterization procedure is not onlycostly, but also painful and inconvenient for the patient.

Medical practitioners have attempted to reduce the risks associated withEMBs by exploring alternative methods for predicting transplantrejection and/or complications from congestive heart failure. Forexample, during the last decade investigators in Europe focused onintramyocardial electrograms and immune system markers that had thepotential for predicting ischemia as well as acute transplant rejection.In studies on canines evaluating data from four myocardial sites, it wasfound that analysis of the mean intramyocardial unipolar peak-to-peakR-wave amplitude had a sensitivity (i.e., an ability to identifyrejection) and a specificity (i.e., percentage of false positives)sufficient for diagnosing most transplant rejection. It also wasdiscovered that, as the number of myocardial leads increases (i.e., thenumber of myocardial sites monitored increases), the sensitivity ofdetecting transplant rejection also increased. Preliminary studies onhumans were able to show a correlation between acute rejection episodesand the mean amplitude of the R-wave of the QRS complex.

Over the past fifteen years, more than one thousand prototype unipolar,peak-to-peak rejection monitors (“UPPRMs”) have been implanted in bothadults and children. UPPRMs require two or more electrodes attached tothe patient's heart that are structured to register QRS voltage. Theamplitude measurement of the intramyocardial electrogram (“IMEG”) wasused to predict rejection.

Another method of conventional rejection monitoring is disclosed in U.S.Pat. No. 5,246,008 to Mueller, which is incorporated herein. Asdisclosed in Mueller, the rejection monitor (“RM”) or telemetrymeasuring unit preferably is connected to the patient's heart using twopairs of current and measuring electrodes in which each currentelectrode is annularly surrounded by a measuring electrode. This RMincludes a miniaturized, battery-operated electronic measuring circuitfor impedance measurement. The RM also has a transmitter-receivercircuit for electromagnetic waves with a carrier frequency of one coilbeing able to function as the antenna. An AC voltage is applied in asquare-wave pulse to the tissue via the current electrodes. Theimpedance of the body tissue is then measured via the measuringelectrodes. The receiver coil of a telemetry control unit can bedisposed on the body of the patient over the RM, preferably during thenight rest periods. The control unit transmits an ON signal via thereceiver coil to the RM via the antenna. The RM then begins applying ACvoltage in a square-wave pulse utilizing the current electrodes andmeasuring the impedance via the measuring electrodes. The RM transmitsthe measured values for a predetermined measuring duration via theinduction coupling formed by the antenna and receiver coil to thecontrol unit. The measured values are stored by the control unit, suchas on a computer, and values can be called in by a clinic using a modemvia a telephone line.

As disclosed in Mueller, the impedance consists substantially of theohmic resistance and a capacitive reactance. The ohmic resistancedepends substantially on the extracellular space of the tissue, whereasthe capacitive reactance depends substantially on the properties of thecell membrane. As a result of ischemia of the tissue during a rejectionreaction, intracellular edema with simultaneous shrinkage of theextracellular space occurs, which results in changes to the ohmicresistance and capacitive reactance of the tissue. The change of thepulse form of the ac voltage is a measure of the impedance. If asquare-pulse voltage is used as the ac voltage, the change of the pulseheight corresponds to the ohmic resistance, whereas the change in thesteepness of the leading edges of the square-wave pulses is a measure ofthe capacitive reactance.

Results have suggested several advantages of these alternative methodsover current methods of transplant rejection assessment such as EMBs. Inparticular, UPPRMs enabled reliable recognition of transplant rejectionepisodes at an early stage, thus allowing prompt treatment to reverserejection and to block further development to more severe stages.Because advanced stages of transplant rejection were not encountered,the amount of additional immuno-suppression necessary to terminaterejection was moderate thereby reducing the treatment costs. Compared toan eighty-five percent (85%) survival rate for one-year post transplantwhen EMBs are used to assess transplant rejection, there were no deathsfrom acute transplant rejection when UPPRMs was used to assessrejection, provided the patient adhered strictly to short-interval, andpreferably daily, IMEG recording. Biopsy findings showed the IMEGs tohave one hundred percent (100%) sensitivity and ninety-seven percent(97%) specificity in detecting transplant rejection and there were 3%false negatives. In those few cases when the UPPRMs indicated transplantrejection with negative biopsy results (reason for less than one hundredpercent (100%) specificity), all of these patients went on to havetransplant rejection within twenty-four (24) to forty-eight (48) hours.

However, simple IMEG amplitude measurement is subject to variation dueto the patient's daily rhythm, exercise status, and medications. A dropin amplitude may not always correlate to a rejection reaction. Moreover,because conventional UPPRMs provide at best only periodic monitoring(i.e., only while the patient is sleeping) the IMEG data registered bythe UPPRMs does not provide the best data for determining a rejectionreaction.

In light of the foregoing, it would be highly desirable to providemethods and apparatus capable of eliminating the risks associated withEMBs while at the same time providing more comprehensive data regardingthe function of a patient's heart. Specifically, the methods andapparatus should allow for continuous, non-invasive monitoring of apatient's heart to thereby accurately detect heart rejection or failureat its earliest phase. In addition, the apparatus and methods shouldpreferably enable medical personnel to obtain historic and real-timemonitoring data and information about the patient's heart so that themedical personnel can more effectively diagnose, discuss, coordinate oralter the patient's treatment.

SUMMARY OF THE INVENTION

The present invention provides non-invasive apparatus and a method formonitoring and evaluating the cardiac function of heart transplant andcongestive heart failure patients, detecting heart failure in suchpatients and providing an appropriate warning to the patient and/orphysician in the event of actual or anticipated heart failure, and/oradministering therapeutic drugs to the patient to treat the patient'scondition.

According to one embodiment, the apparatus for monitoring a patient'sheart includes a registering unit structured to be implanted into thepatient's body. The registering unit includes a first controller inelectrical communication with the patient's heart. The first controlleris structured to register an electrical signal from the patient's heart.The apparatus includes a second controller in operable communicationwith the first controller of the registering unit. The second controllerincludes a data repository structured to receive data corresponding tothe registered electrical signal and structured to store the data. Thedata repository of the second controller stores data corresponding to abaseline electrical signal of the patient's heart. The second controlleris structured to receive the data from the first controllercorresponding to the registered electrical signal. In one construction,the registering unit includes a transmitter in operable communicationwith the second controller. In another construction, the registeringunit is in at least one of electrical or optical communication with thesecond controller. In still another construction, the data repositoryelectrically or magnetically stores the data corresponding to theregistered electrical signal.

According to another embodiment, the apparatus includes a relay unit inoperable communication with the first controller of the registeringunit. The relay unit is structured to receive data from the firstcontroller corresponding to the registered electrical signal. Theapparatus includes a second controller in operable communication withthe relay unit. The second controller includes a data repositorystructured to receive data from the relay unit corresponding to theregistered electrical signal and structured to store the data. The datarepository of the second controller stores data corresponding to abaseline electrical signal of the patient's heart. The second controlleris structured to receive the data from the relay unit corresponding tothe registered electrical signal. In one construction, the registeringunit further comprises a transmitter in operable communication with therelay unit. In another construction, the registering unit is in at leastone of electrical or optical communication with the relay unit. Inanother embodiment, the relay unit communicates with the secondcontroller via a computer network.

The second controller is structured to compare the registered electricalsignal to the baseline electrical signal to determine whether thepatient's heart is functioning properly. According to one construction,the second controller is structured to generate a first templatecorresponding to the baseline electrical signal and a second templatecorresponding to the registered electrical signal. The second controlleris structured to measure the area between the first template and thesecond template to determine whether the patient's heart is functioningproperly. In another construction, the second controller is structuredto identify a plurality of comparison points for the first template andto identify a plurality of comparison points for the second template.Each of the plurality of comparison points for the second templatecorresponds to one of the comparison points for the first template. Thesecond controller is further structured to measure differences betweeneach of the corresponding plurality of comparison points for the firsttemplate and the second template to determine whether the patient'sheart is functioning properly.

The present invention also provides a computer program product formonitoring a patient's heart. The computer program product includes acomputer-readable storage medium having computer-readable program codeportions stored therein. According to one embodiment, thecomputer-readable program portions include an executable portion forreceiving data representing a registered electrical signal from thepatient's heart and a baseline electrical signal of the patient's heart.The executable portion compares the registered electrical signal to thebaseline electrical signal to determine whether the patient's heart isfunctioning properly. In one form, the executable portion generates afirst template corresponding to the baseline electrical signal and asecond template corresponding to the registered electrical signal. Theexecutable portion then measures the area between the first template andthe second template to determine whether the patient's heart isfunctioning properly. In another form, the executable portion identifiesa plurality of comparison points for the first template and identifies aplurality of comparison points for the second template. Each of theplurality of comparison points for the second template corresponds toone of the comparison points for the first template. The executableportion measures differences between each of the corresponding pluralityof comparison points for the first template and the second template todetermine whether the patient's heart is functioning properly.

The present invention also provides a method for monitoring a patient'sheart. According to one embodiment, the method includes implanting aregistering unit into a patient's body. At least one pair of electrodesis implanted into the patient's body in electrical communication withthe patient's heart. The method includes registering an electricalsignal from the patient's heart. Data corresponding to the registeredelectrical signal is communicated from a first controller to a secondcontroller. In one form, the data representing the registered electricalsignal is stored in computer-readable memory.

The method includes comparing the registered electrical signal to abaseline electrical signal to determine whether the patient's heart isfunctioning properly. In one form, the comparing step includesgenerating a first template corresponding to the baseline electricalsignal. A second template corresponding to the registered electricalsignal is generated. Thereafter, the area between the first template andthe second template is measured to determine whether the patient's heartis functioning properly. In another form, the comparing step includesidentifying a plurality of comparison points for both the first templateand second template. Each of the plurality of comparison points for thesecond template corresponds to one of the comparison points for thefirst template. The differences between each of the correspondingplurality of comparison points for the first template and the secondtemplate are then measured to determine whether the patient's heart isfunctioning properly.

Thus, there is provided methods and apparatus capable of eliminating therisks associated with EMBs while at the same time providing morecomprehensive data regarding the function of a patient's heart. Thesemethods and apparatus allow for accurate, non-invasive monitoring of apatient's heart to thereby detect heart rejection or failure at itsearliest phase. In addition, the apparatus and methods enable medicalpersonnel to obtain historic and real-time monitoring data andinformation about the patient's heart so that the medical personnel canmore effectively diagnose, discuss, coordinate or alter the patient'streatment.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other advantages and features of the invention, andthe manner in which the same are accomplished, will become more readilyapparent upon consideration of the following detailed description of theinvention taken in conjunction with the accompanying drawings, whichillustrate preferred and exemplary embodiments, and which are notnecessarily drawn to scale.

Six figures have been selected to illustrate the present invention.

FIG. 1 is a diagram illustrating a system for monitoring a patient'sheart, according to one embodiment of the present invention;

FIG. 2 is a block diagram illustrating a measuring unit, according toone embodiment of the present invention;

FIG. 3 is a diagram showing a digitized electrogram or template,according to one embodiment of the present invention;

FIG. 4 is a diagram graphically illustrating a comparison of a firsttemplate, which corresponds to a registered electrical signal from apatient's heart, to a second template, which corresponds to a baselineelectrical signal from the patient's heart, according to one embodimentof the present invention;

FIG. 5 is a diagram graphically illustrating a comparison of a firsttemplate, which corresponds to a registered electrical signal from apatient's heart, to a second template, which corresponds to a baselineelectrical signal from the patient's heart, according to one embodimentof the present invention; and

FIG. 6 is a flow chart illustrating a method of monitoring a patient'sheart, according to one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, these embodiments of theinvention may take many different forms and should not be construed aslimited to the embodiments set forth herein; rather, these embodimentsare provided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

Referring to FIG. 1, there is illustrated a system 10 for monitoring theheart 12 of a heart transplant patient or a patient suffering congestiveheart failure. The system 10 includes an implantable registering unit 14for non-invasive monitoring of a patient's heart 12, a relay unit 16 forinterrogating the registering unit, and a controller 18 for receivingdata from the relay unit 16 corresponding to the patient's heart andanalyzing the data. The registering unit 14 is structured to beimplanted into the patient's body 20 and, thus, preferably includes ahousing 22 constructed of a relatively rigid material that isbiologically inert, such as titanium and silicone. As illustrated inFIG. 2, the registering unit 14 can include a controller 24, such as acomputer, microprocessor, or central processing unit operating undersoftware control, an energy source 26, a receiver 30, and atransmitter/antenna 32. The registering unit 14 can optionally include agenerator 28 structured to provide electrical stimulus to the patient'sheart, a therapeutic process commonly referred to as “pacing.” The useof electrical stimuli to treat disorders such as bradyarrhythmias, orslow heart rhythms, and tachyarrhythmias, or fast heart rhythms, is wellknown to those skilled in the art and will not be further describedherein. The energy source 26 is structured to provide electrical orthermal energy to the other components of the registering unit 14,including the controller 18, generator 28, receiver 30, and/ortransmitter/antenna 32. The transmitter/antenna 32 is structured tocommunicate with the relay unit 16 electrically, such as through radiofrequency communication, or optically. In one embodiment, thetransmitter/antenna 32 includes an induction coil (not shown) that isstructured to communicate with a corresponding induction coil (notshown) in the relay unit 16. Any commercially available pacemaker withappropriate software modifications can be used as the registering unit14.

As illustrated in FIGS. 1 and 2, the controller 24 is in electricalcommunication with the patient's heart 12 via one or more sets or pairsof electrodes 34. According to one construction, as illustrated in FIG.1, the system 10 includes two pairs of electrodes 34. The electrodes 34can comprise any one of a number of commercially available epicardial(outside the surface of the heart) or endocardial (inside the heart)electrodes, as is well known to those skilled in the art. According toone embodiment, the electrodes 34 comprise screw-in epicardial bipolarIS I leads. The electrodes 34 preferably are attached to the heart 12 atthe left and right ventricles, and left and right atriums. Theelectrodes 34 can be positioned at other areas about the patient's heart12, depending on a variety of factors including, but not limited to,whether the patient is a heart transplant patient or suffering fromcongestive heart failure, the physical characteristics of the patientsheart, or need for cardiac pacing. The electrodes 34 can be modified toinclude pressure sensors, which gauge vigor or degree of myocardialcontraction.

The controller 18 can include a computer, microprocessor, or centralprocessing unit operating under software control. As illustrated in FIG.1, the controller 18 preferably comprises a data depository 36comprising hardware and associated software for data storage. The datarepository 36 is in operable communication with the controller 18 viaappropriate wiring or circuitry (not shown). The data repository 36 isstructured to receive and store in computer-readable memory datacorresponding to the electrical signals received from the patient'sheart 12. The relay unit 16 is structured to transmit to the controller18 data corresponding to the electrical signals received from thepatient's heart 12 and to receive instructions transmitted by thecontroller 18 and transmit these instructions to the controller 24 ofthe registering unit 14 via the transmitter/antenna 32.

According to one construction, the controller 18 is located at the samelocation as the relay unit 16 and the patient, such as at a medical carefacility or office or at the patient's home. For example, the relay unit16 can be connected in operable communication with the controller 18through a serial port connection or through a USB connection. Accordingto another construction, the controller 18 is disposed remotely from therelay unit 16 and the patient. According to this construction, the relayunit 16 comprises another controller, such as a computer,microprocessor, or central processing unit operating under softwarecontrol, that is in operable communication with the controller 18 via acomputer network, including, but not limited to, the internet, a localarea network, a wide area network, a wireless network (such assatellite), a dial-up modem, etc., so that the relay unit 16 cancommunicate with the controller 18.

Advantageously, this later embodiment eliminates the need to have ananalog/digital converter or demodulator at the patient testing center.

Referring to FIGS. 1 and 2, when monitoring a patient's heart 12, thecontroller 18, either automatically at predetermined intervals orpursuant to instructions from an operator, communicates instructions tocontroller 24 of the registering unit 14 via the communication linkbetween the relay unit 16 and transmitter/antenna 32 of the registeringunit 14, instructing the registering unit to initiate monitoring of thepatient's heart. The controller 24 then instructs the receiver 30 tobegin registering or sensing the electrical signals emitted by thepatient's heart. Data corresponding to the electrical signals registeredby the receiver 30 is communicated to the controller 24. The controller24 communicates the data representing the electrical signals registeredby the receiver 30 to the transmitter/antenna 32, which thencommunicates the data to the relay unit 16. The relay unit 16 in turncommunicates the data to the controller 18 for analysis.

The controller 18 operating under associated software control allowsprecise discrimination of intracellular and extracellular myocardialdynamics, as well as volume changes and myocardial strength ofcontraction in the patient's heart 12. The controller 18 is structuredto analyze the data received from the patient's heart 14 in severalways. According to one procedure, each time the controller 18 receivesdata corresponding to the electrical signals received by the registeringunit 14 from the patient's heart 12, the controller 18 digitally createsor generates a graphical representation, such as a waveform, graph, orchart (referred to herein as a “template”), of a patient's intracardiacelectrogram, such as the one illustrated in FIG. 3. For example,according to one form, the electrical signals received from thepatient's heart comprise analog electrogram signals that are digitizedby the controller 18 at 1 KHz with a 12-bit resolution and stored in thedata repository 36 for later analysis. Preferably, a baseline electricalsignal is registered using the above-referenced procedure to produce atemplate of the baseline electrical signal that is stored in the datarepository 36 for later analysis. The baseline electrical signal can beobtained when the patient undergoes heart transplant, when theregistering unit 14 is implanted, or at some other predetermined time.

The generation of the graphical representations by the controller 18 caninclude, but is not limited to: (1) individual beat identification (viapeak detection algorithms); (2) Fourier decomposition of selected beatsor beat sequences; (3) Fourier coefficient averaging and average signalreconstruction, assessing the average heart beat of the patient (asderived or computed from the data corresponding to the registeredelectrical signals received from the patient's heart 12, for criticaltime, area, derivative and amplitude markers using standard techniques);(4) utilizing Fourier coefficients and average waveform markers asdescriptors of the graphical representation and comparing them usingeither time-series or auto- and cross-correlation analysis techniques;(5) constructing a modified wavelet template and performing a criticalmatch percent correlation; (6) transforming wavelets, which arefragments of a complete waveform, to identify frequency and/or scalecomponents of a signal simultaneously with their location in time; (7)using wavelet transformation that entails scale analysis via creation ofmathematical structures that provide varying time/frequency/amplitudeslices of a waveform for analysis.

The analysis by the controller 18 of the digitized electrograms ortemplates for the baseline electrical signal and the registeredelectrical signal involves comparing the templates to determine whethera predetermined critical match-percent threshold between the templateshas been exceeded. For example, the analysis can include a modifiedwavelet template construction and a critical match percent correlation.Wavelet transformation (WT) identifies frequency or scale components ofa signal and simultaneously with its location in time. Thetransformation entails scale analysis via creation of mathematicalstructures that provide varying time/frequency/amplitude slices foranalysis. Each transformation is a fragment of a complete waveform andis termed as “wavelet.” Wavelets are optimal for approximating data withsharp discontinuities, such as myocardial electrograms. Since a percentwavelet match for a given heart rhythm is stable with regard to changesin body position and exercise over time, this algorithm offers greatersensitivity than conventional techniques, such as morphology algorithms(i.e., UPPRM), that analyze the amplitude of selected of a electrogram.

According to one embodiment, as illustrated in FIG. 5, the templates forthe baseline electrical signal and the registered electrical signal arecompared by measuring the area of discrepancy between the templates anddetermining a comparison percentage match, which can then be used toaccess whether the patient's heart is functioning properly. According toanother embodiment, as illustrated in FIG. 6, the comparison involvesidentifying a plurality of comparison points for the baseline templateand identifying a plurality of comparison points for the templatecorresponding to the registered electrical signal. Each of the pluralityof comparison points for the second template corresponding to one of thecomparison points for the baseline template. Thereafter, a correlationof points in the template will provide a comparison percentage matchbetween the two templates, which can then be used to access whether thepatient's heart is functioning properly.

A critical match-percentage threshold under either method (i.e., adiscrepancy in the match points) of over thirty percent (30%), or morepreferably, twenty (20%), or still more preferably, ten percent (10%)would indicate acute heart rejection. Thus, if a subsequent templatecorresponding to an electrical signal received from the patient's heart12 does not correlate to the baseline template, by greater than seventypercent (70%), more preferably greater than eighty percent (80%), andstill more preferably greater than ninety percent (90%), then rejectionis present. Early detection of rejection advantageously permits promptinitiation of life saving therapy.

The present invention also provides a method for monitoring a patient'sheart. According to one embodiment, the method includes implanting aregistering unit into a patient's body. See Block 60. At least one pairof electrodes is implanted into the patient's body in electricalcommunication with the patient's heart. See Block 62. The methodincludes registering an electrical signal from the patient's heart. SeeBlock 64. Data corresponding to the registered electrical signal iscommunicated from a first controller to a second controller. See Block66. In one embodiment, the data representing the registered electricalsignal is stored in computer-readable memory. See Block 68.

The method includes comparing the registered electrical signal to abaseline electrical signal to determine whether the patient's heart isfunctioning properly. See Block 70. In one embodiment, the comparingstep includes generating a first template corresponding to the baselineelectrical signal. See Block 72. A second template corresponding to theregistered electrical signal is generated. See Block 74. Thereafter, thearea between the first template and the second template is measured todetermine whether the patient's heart is functioning properly. See Block76. In another embodiment, the comparing step includes identifying aplurality of comparison points for both the first template and secondtemplate. See Block 78. Each of the plurality of comparison points forthe second template corresponds to one of the comparison points for thefirst template. The differences between each of the correspondingplurality of comparison points for the first template and the secondtemplate are then measured to determine whether the patient's heart isfunctioning properly. See Block 80.

FIGS. 1, 2 and 6 are block diagrams, flowcharts and control flowillustrations of methods, systems and program products according to theinvention. It will be understood that each block or step of the blockdiagrams, flowcharts and control flow illustrations, and combinations ofblocks in the block diagrams, flowcharts and control flow illustrations,can be implemented by computer program instructions. These computerprogram instructions may be loaded onto a computer or other programmableapparatus to produce a machine, such that the instructions which executeon the computer or other programmable apparatus create means or devicesfor implementing the functions specified in the block diagrams,flowcharts or control flow block(s) or step(s). These computer programinstructions may also be stored in a computer-readable memory that candirect a computer or other programmable apparatus to function in aparticular manner, such that the instructions stored in thecomputer-readable memory produce an article of manufacture, includinginstruction means or devices which implement the functions specified inthe block diagrams, flowcharts or control flow block(s) or step(s). Thecomputer program instructions may also be loaded onto a computer orother programmable apparatus to cause a series of operational steps tobe performed on the computer or other programmable apparatus to producea computer implemented process such that the instructions which executeon the computer or other programmable apparatus provide steps forimplementing the functions specified in the block diagrams, flowchartsor control flow block(s) or step(s).

Accordingly, blocks or steps of the block diagrams, flowcharts orcontrol flow illustrations support combinations of means or devices forperforming the specified functions, combinations of steps for performingthe specified functions and program instruction means or devices forperforming the specified functions. It will also be understood that eachblock or step of the block diagrams, flowcharts or control flowillustrations, and combinations of blocks or steps in the blockdiagrams, flowcharts or control flow illustrations, can be implementedby special purpose hardware-based computer systems which perform thespecified functions or steps, or combinations of special purposehardware and computer instructions.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

1. A system for monitoring a patient's heart, comprising: a registeringunit configured to be implanted into the patient's body, saidregistering unit comprising a first controller in electricalcommunication with the patient's heart, said first controller beingconfigured to register an electrical signal emitted by the patient'sheart; and a second controller in operable communication with said firstcontroller, said second controller being configured to receive the datafrom said first controller corresponding to the registered electricalsignal and to compare the registered electrical signal to a baselineelectrical signal emitted by the patient's heart to determine whetherthe patient's heart is functioning properly, wherein in comparing theregistered and baseline electrical signals, said second controller isconfigured to generate a template of an intracardiac electrogram foreach of the registered electrical signal and a baseline electricalsignal and to compare the templates to determine whether the patient'sheart is functioning properly, wherein said second controller isconfigured to determine whether a predetermined critical match-percentthreshold has been exceeded based on a comparison of the templates forthe registered electrical signal and the baseline electrical signal,wherein the critical match-percent threshold comprises at least 70%correlation between the templates for the registered electrical signaland the baseline electrical signal, and wherein a critical-match percentthreshold less than 70% indicates that the heart is not functioningproperly.
 2. The system of claim 1, wherein said registering unitfurther comprises a transmitter in operable communication with saidsecond controller.
 3. The system of claim 1, further comprising a relayunit independent of said first controller and said second controller andconfigured to communicate with said first controller and said secondcontroller, said relay unit being configured to receive data from saidfirst controller corresponding to the registered electrical signal andto transmit the received data to said second controller.
 4. The systemof claim 3, wherein the relay unit is configured to wirelesslycommunicate with said registering unit.
 5. The system of claim 1,wherein said second controller is located remotely from said registeringunit.
 6. The system of claim 1, wherein said second controller includesa data repository for storing data corresponding to the registeredelectrical signal and data corresponding to the baseline electricalsignal of the patient's heart.
 7. The system of claim 1, furthercomprising a plurality of electrodes in electrical communication withsaid registering unit and configured to be coupled directly to theheart.
 8. The system of claim 1, wherein the critical match-percentthreshold comprises at least 80% correlation between the templates forthe registered electrical signal and the baseline electrical signal,wherein a critical-match percent threshold less than 80% indicates thatthe heart is not functioning properly.
 9. The system of claim 1, whereinthe critical match-percent threshold comprises at least 90% correlationbetween the templates for the registered electrical signal and thebaseline electrical signal, wherein a critical-match percent thresholdless than 90% indicates that the heart is not functioning properly. 10.The system of claim 1, wherein said second controller is configured togenerate a first template corresponding to the baseline electricalsignal and a second template corresponding to the registered electricalsignal, said second controller configured to measure the area betweenthe first template and the second template to determine whether thepatient's heart is functioning properly.
 11. The system of claim 1,wherein said second controller is configured to generate a firsttemplate corresponding to the baseline electrical signal and a secondtemplate corresponding to the registered electrical signal, said secondcontroller being configured to identify a plurality of comparison pointsfor the first template and to identify a plurality of comparison pointsfor the second template, each of the plurality of comparison points forthe second template corresponding to one of the comparison points forthe first template, and wherein said second controller is configured tomeasure differences between each of the corresponding plurality ofcomparison points for the first template and the second template todetermine whether the patient's heart is functioning properly.
 12. Thesystem according to claim 1, wherein said registering unit furthercomprises a housing of biologically inert material for housing saidfirst controller.
 13. The system of claim 1, wherein said secondcontroller is configured to calculate a quantifiable difference betweenthe registered electrical signal and the baseline electrical signalbased on the comparison between the signals in order to determinewhether the patient's heart is functioning properly.
 14. The system ofclaim 1, wherein said second controller is configured to compare theregistered electrical signal to the baseline electrical signal followinga heart transplant in order to determine whether the patient'stransplanted heart is being rejected.
 15. A system for monitoring apatient's heart, comprising: a registering unit configured to beimplanted into the patient's body, said registering unit comprising afirst controller in electrical communication with the patient's heart,said first controller being configured to register an electrical signalemitted by the patient's heart; and a second controller in operablecommunication with said first controller, said second controller beingconfigured to receive the data from said first controller correspondingto the registered electrical signal and to compare the registeredelectrical signal to a baseline electrical signal emitted by thepatient's heart to determine whether the patient's heart is functioningproperly, wherein said second controller is configured to compare theregistered electrical signal to the baseline electrical signal followinga heart transplant in order to determine whether the patient'stransplanted heart is being rejected.